The present invention relates to a power check meter, and in particular to a power check meter with improved data transmission characteristics.
Some electrical power customers tap the electrical power line routed to their residence or business at a location prior to their power meter in order to steal electrical power from the utility. To reduce the theft of electrical power many utilities use a portable kilowatt-hour check meter connected to the incoming power line of a suspected dishonest customer to monitor the customer's power usage. The portable check meter is normally installed high on the power pole near the location that the customer's line connects to the utility's main power line. By installing the portable check meter in such a location it is difficult for the customer to tap the incoming line prior to the portable check meter. The utility compares the recorded power usage from both the power meter and the portable check meter during the same time period and notes any difference. If the measurements are significantly different then the utility has confirmed its suspicions and obtained proof that electrical power has been stolen by the customer. The utility then takes corrective measures to ensure that the customer thereafter refrains from stealing electrical power.
Customers that steal electrical power are paranoid of being caught and may notice the utility employees installing the portable check meter on the pole near their location. If the customer notices utility employees installing such equipment, the customer will typically refrain from stealing power for a period of time. During such a time the utility will not be able to detect the theft of power. Traditionally, in order to monitor the customer's power usage, utility employees were required to be in close proximity to the portable check meter's display indicating power usage. This required a utility employee to climb the pole which may alert dishonest customers that their power usage is being monitored and cause the customer to refrain from stealing power until they are confident that their power usage is not being monitored. In addition, it is frequently dangerous for utility employees to be near such dishonest customers, especially if they are involved in illegal drug activities.
In order to alleviate the need for utility employees to be within several feet of the traditional portable check meter to read the power usage, some portable check meters include a radio-frequency transmitter that periodically transmits the power usage. The utility employee uses a radio-frequency receiver to receive and display the transmitted power usage. However, the radio-frequency receiver must still be within approximately 100 to 300 feet to receive the power usage. Accordingly, the utility employee must still get close to the customer which may inadvertently alert the customer that they are being monitored. Also, this may place the utility employee in a dangerous situation. In addition, this requires the utility employee to drive to the vicinity of the transmitter requiring significant time and expense. Further, the utility must obtain a specialized receiver to receive the power usage at additional expense. Such a system is available from Universal Protection Corporation of Atlanta, Ga., known as CMI Diversion Check Meter System.
An alternative portable check meter available from Universal Protection Corporation of Atlanta, Ga., sold under the name CPS I Cellular Phone System, further includes a cellular phone link. A radio-frequency transmitter is used to transmit power usage from the portable check meter to a radio-frequency receiver located in a separate housing. The radio-frequency receiver receives the power usage and in response retransmits the power usage as digital data to the utility using a cellular telephone transmitter. The utility needs a computer, a modem, and specialized software to receive and analyze the digital data from the cellular telephone transmitter. However, the CPS I system requires two separate enclosures to be mounted in the vicinity of the customer which increases the likelihood that the customer will notice the check meter. In addition, the utility is required to use specialized software operating on the computer to receive and analyze the data obtained from the cellular phone transmitter. Further, cellular telephone communications are highly susceptible to dropouts which then require the data to be retransmitted until valid data is received by the utility. The dropouts and potential corruption of the digital data increases the likelihood that the utility will obtain a false reading of the actual power usage.
Portable check meters normally include both a voltage input (or transformer) that is directly connected to the wire to sense voltage and a current transformer that encircles the wire to sense current flowing within the wire. The voltage and current measurements are multiplied together to obtain the power usage. Unfortunately, utility employees periodically install the current transformer in the reverse direction thereby causing the current induced in the current transformer to have the wrong polarity. The improper current polarity may result in the portable check meter calculating an incorrect power usage. If the current transformer is not properly connected to the wire then the utility employee must return to and reconnect the current transformer to the wire with the proper orientation. The utility employee returning to the check meter increases the likelihood that the customer will detect the monitoring of their power usage and also subjects the utility employee to further danger.
What is desired, therefore, is a portable check meter that reduces the likelihood of transmitting false data to the utility. Also, the check meter should eliminate the need for a computer and specialized software to receive and display the power usage while minimizing the amount of equipment installed at the customer. Further, the check meter should minimize the time necessary for installation and ensure that the utility employee orientates the current transformer in the proper direction. In addition, the check meter should reduce the need for utility employees to be in the vicinity of the customer after installation.